The present invention relates to a fastener system, and in particular to a fastener system having an internally threaded female member and an externally threaded male member.
Many types of threaded fastener systems are known, including my fastener system disclosed in U.S. Pat. No. 4,901,426 utilizing a male member with a rectangular end portion having thread segments pressed into the edges or corners of the rectangular end portion which mate with the internal threads of a female member. In such a device, torque was selected by adjusting the position of the thread segments axially relative to one another to provide an interference thread between adjacent thread segments. However, the torque required for insertion of such a fastener increased as the male member was inserted further into the female member due to an increasing number of interference threads being engaged.
Although not limited to any particular application or environment, the fastener system of the present invention has utility in pedal rods used in brakes for automotive vehicles and more particularly to such a brake wherein an annular resilient diaphragm is clamped around its outer perimeter by a pair of annular housing or shell members defining spaced vacuum chambers at opposite sides of the diaphragm. The diaphragm has a central opening tightly clamping an annular valve body in an air-tight snap fit within an annular groove thereof. The valve body is urged into one of the vacuum chambers in response to pressure of an operator's foot on a brake pedal, driving a clevis of a pedal rod into the valve body and thereby urging the valve body against a compression rod assembly which in turn actuates the piston of a conventional master cylinder containing liquid which actuates the pistons of the wheel brakes. As the pedal rod is urged into the valve body, atmospheric pressure is admitted to one of the chambers while the other chamber containing the compression rod assembly is under vacuum. This causes atmospheric pressure to apply the wheel brakes in response to very slight pressure on the brake pedal.
In a known clevis style pedal rod assembly, four separate parts are utilized to form the assembly. A first piece comprises a U-shaped clevis member which has, as a second piece, a nut, welded thereto. A threaded rod with a separate nut is threaded into the nut captured on the clevis and the two nuts are then locked together to join the pieces in final assembly. Such an assembly requires an excessive number of parts and also entails a high manufacturing cost, particularly in the welded assembly of the first nut to the clevis member.
However, any assembly for the appliance industry, automobile industry, farm equipment industry, air conditioning industry, aircraft industry, military vehicles industry, etc. would be applicable for a fastening system embodying the principles of the present invention where there is vibration potential or requirement of torque control.
It would be an improvement in the art if a fastener system utilizing a small number of parts were provided which allows for repeatability or reuse of the fastener and allows for the same selected torque each time the fastener is used. It would also be an improvement in the art if a fastener system were provided which could provide a clevis style or other non-linear configuration male member while reducing the cost and the number of parts necessary for such an assembly. Also, it would be an improvement in the art if a fastener system were provided which allows for selecting a desired maximum torque for assembling and disassembling a male and female member, which torque remains constant during assembly and disassembly of the two parts.